In the sport of rappelling, a person equipped to rappell typically has a belt or a harness wrapped around or near his waist to which a rappelling descender is attached by a link called a carabiner. A rappelling descender is a device through which rope is passed, forming turns of rope around structures of the descender, each turn increasing the friction of the rope against the descender for slowing the descent of the rappeller.
Before beginning the descent, a person prepared to rappell weaves a series of turns of rope through the descender that will be maintained throughout the entire rappell, without change as to the number of turns or their placement. Once the rappeller begins the descent, he has committed himself to dropping at a given speed with a given amount of control over the speed. Dramatically slowing the speed of descent cannot usually be effected once the rappell has begun, which causes problems if the rappeller desires to slow down or stop.
Conventional descenders are shown throughout a book entitled Rappelling, Edition II, by Tom Martin, specifically on page 6-15, shown in FIG. 6-12. Descenders of the type shown in this illustration have a tendency to form a knot, as shown in FIG. 6-14, which causes the rappeller to suddenly stop his descent. The rappeller must attempt to either cut himself free from the rope or untie the knot in order to reach his destination.
In order to prevent knotting of the rope, descenders, such as those shown in FIG. 6-17, have been provided with ears projecting outwardly from opposite sides of the central opening of the descender. These ears prevent the rope turns from sliding together and knotting.
In FIGS. 6-54 through 6-57, another descender is illustrated which has ears for preventing knotting and also through which the rope may be wound to slow the descent. The orientation of this descender is difficult to predict due to the shape of the hole to which the carabiner is attached and through which the rope is wound. The ears of the descender are likely to be positioned anywhere from almost directly upward, as shown in FIG. 6-54, to nearly directly downward because the descender is not stable in any orientation. This makes it difficult to reliably loop the rope around the ears to slow the descent since the location of the ears varies during the descent.
Another descender is shown in FIG. 6-77, but this descender provides little access to wrapping the rope around the descender's ears. This is due to the orientation of the ears and their proximity to the taut overhead rope. It would be difficult to loop the loose rope coming out of the bottom of the descender around the ears, since the ends of the ears are so close to the overhead rope and the overhead rope would have to be moved to get past it to the ears.
Another descender is shown in FIGS. 6-118 through 6-120, which operates using the same principles as the descender shown in FIG. 6-54. The carabiner, which is the link connected between the descender and the rappeller's belt, takes a preferred position at the lower end of the descender, keeping the ears in a side orientation. The carabiner may interfere with the rope wound through the oval shaped loop, and wrapping the rope around the ears may be somewhat difficult due to the angle formed between the ears and the loop. This angle makes putting the rope between the ears and the loop a task requiring time and manipulation.
In U.S. Pat. No. 4,774,742 to Johnson, a descender is disclosed having a circular ring with a capstan extending from one side. The capstan has ears for preventing a rope from sliding off the capstan, and a secondary ring extends downwardly from the circular ring for attachment to the belt or carabiner. The descent of the rappell using Johnson's descender is controlled by wrapping the rope around the secondary ring attached to the belt. Wrapping the rope as required by Johnson requires the use of both hands as the rope is transferred from one side of the descender around the downwardly projecting secondary ring and back around to the side from which it came.
U.S. Pat. No. 3,678,543 to Hobbs discloses a descender having generally a "C" shape, with an extended loop beneath the "C" to which a carabiner is attached. The Hobbs device has rope wound through it in a conventional manner, but has a lower leg around which a loop of rope may be wound for slowing or stopping a descent. Hobbs' device requires a loop to be formed in the rope and looped over the lower leg, which is a maneuver that would be difficult during a descent, and in which the likelihood of failing is substantial.
U.S. Pat. No. 1,565,041 to Arney discloses an adjusting loop which can be used as a descender. As a descender, rope would be passed through the central loop and the end loop would be attached to the rappeller's belt with a carabiner. Rope coming through the central loop could be wound around the projections extending from the end opposite the carabiner to slow the rappeller's descent. Looping around these projections would be extremely difficult since the overhead, taut rope would inhibit this wrapping motion. Even if wrapping were possible, this would be a two-handed maneuver, which increases the danger involved.
U.S. Pat. No. 1,713,106 to Ulfers shows a rope lock which could be used as a descender. Due to the directions of the projections extending from the rope lock, this device would be extremely difficult to use as a descender, especially in terms of slowing the descent after beginning the rappell.
A descender is needed which permits a person using it to adjust the speed of his descent during the rappell in a quick, predictable, certain and safe manner. For rescue and military use especially, a descender is needed which can permit stopping of a rappell leaving both hands free for other uses, such as assisting the endangered person or handling a weapon.